The present invention relates to an image display apparatus for displaying an image on a plane of a device, such as an EL display device, plasma display device or electro-emission type fluorescence display device.
FIG. 15 shows a configuration of a display apparatus in the prior art.
A reference numeral 1 refers to a display panel using a surface conduction type electro-emission device. Scanning lines Dx1 to Dxm in a row direction and modulation lines Dy1 to Dyn in a column direction are arranged in matrix, and electro-emission devices, not shown, are placed on the intersection points of the lines to form m rows and n columns of electro-emission devices. When an electric current flows through this device, electrons are emitted, wherein a non-linear characteristic shown in FIG. 16 is showed. For instance, when a voltage of 16 V is applied to the device, electrons are emitted, but when a voltage of 8 V is applied, almost no electrons are emitted. Then, the emitted electrons are accelerated by accelerating means, not shown, to cause the electrons to impinge on a fluorescent face, not shown, so that light is emitted. In other words, the device to which a voltage of 16 V is applied can emit light, but the application of 8 V that is half of it does not lead to light emission. Therefore, simple matrix driving is possible as shown in FIG. 17.
A reference numeral 2 refers to a scanning driving section. The scanning driving section 2 is comprised of a switching switch 22, a selection potential generating section 23 and a non-selection potential generating section 24. A reference numeral 3 refers to a modulation driving section. The modulation driving section 3 is comprised of a shift resistor 31, a latch 32, a pulse width modulation circuit 33, a driving amplifier 34. A reference numeral 4 refers to a synchronization separating section. A reference numeral 5 refers to an A-D converter. A reference numeral 6 is a driving control circuit for generating a driving control signal. A reference numeral 7 refers to a resolution converting section. A reference numeral 10 refers to an input signal identifying section. A reference numeral 11 refers to an input control section. A reference numeral 12 refers to a resolution converting control section.
A reference symbol S1 refers to an analog video signal inputted to the apparatus. A reference symbol S2 refers to a synchronizing signal separated from the analog video signal S1. A reference symbol S3 refers to a digital video signal obtained by sampling the video signal S1 in the A-D converter 5. A reference symbol S4 refers to a display signal obtained by subjecting the digital video signal to an image processing. A reference symbol S5 refers to a conversion timing signal applied to the A-D converter 5. A reference symbol S6 refers to a conversion parameter for defining an operation of the resolution converting section 7. A reference symbol S7 refers to an image clock signal for controlling an operation of a shift register. A reference symbol S8 refers to a modulation control signal for controlling an operation of the modulation driving section 3. A reference symbol S9 refers to a PWM clock that serves as an operation basis for the pulse width modulation circuit. A reference symbol S10 refers to a scanning control signal for controlling an operation of the scanning driving section. A reference symbol S11 refers to an image type signal obtained by making identification in the input identifying section.
The synchronizing signal S2 extracted from the analog video signal S1 inputted to the apparatus by the synchronization separating section 4 is inputted to the driving control circuit 6 and the input identifying section 10.
The input identifying section 10 measures timing of the synchronizing signal, and identifies a type of the video signal being inputted thereto to output the image type signal S11.
The driving control circuit 6 generates different kinds of driving control signals S7 to S10 on the basis of the synchronizing signal S2 and the image type signal S11.
The input control section 11 outputs a conversion timing signal S5 for operating the A-D converter 5 in accordance with the synchronizing signal S2 and the video kind signal S11.
The A-D converter 5 receives and samples the analog video signal S1 in accordance with the conversion timing signal S5 to output the digital video signal S3.
The resolution converting control section 12 determines different kinds of parameters necessary for the conversion of resolution in accordance with the image type signal S11 to output the conversion parameter S6.
The resolution converting section 7 receives the digital video signal S3, and subjects it to a resolution conversion in accordance with the conversion parameter S6 to output the display signal S4.
An operation in which the display panel 1 is driven by the scanning driving section 2 and the modulation driving section 3. FIG. 18 shows timing in this occasion.
The modulation driving section 3 sequentially inputs the display signal S4 to the shift register 31 in synchronization with the image clock signal S7, and holds the display data in the latch 14 in accordance with a LOAD signal of the modulation control signal S8. Then, responsive to a START signal of the modulation control signal S8, a pulse signal having a pulse width according to the data held in the latch 32 is generated by the pulse width modulation circuit 33 on the basis of the PWM clock S9, and a voltage is amplified to Vm in the amplifier 34 to drive the modulation lines of the display panel 1.
In the way of the above operations, the contents of the input video signal S1 are displayed on the display panel 1.